1. ELECTROMAGNETIC SPECTRUM

2. Electromagnetic spectrum
• Distribution of the continuum of all radiant energies can be
plotted either as a function of wavelength or of frequency in a
chart known as the electromagnetic spectrum
• It ranges from shorter wavelengths (including X-rays and
gamma rays) to longer wavelengths (microwaves and radio
waves)

4. • electromagnetic spectrum is the range of all
possible frequencies of
electromagnetic radiation
• EMR extends over a wide range of energies or
wavelengths or frequencies

5. The electromagnetic waves are grouped into types that have similar
wavelengths and so have similar properties.
Electromagnetic waves form a continuous series in order of changing
wavelength, frequency and energy. This series is called the electromagnetic
spectrum.
gamma
raysX-raysultraviolet
visible
lightinfraredmicrowaves
radio
waves
0.01nm100nm 1nm0.01mm1mm10cm100m
smaller wavelength
higher frequency, energy and hazard.

6. • Radio: Your radio captures radio waves emitted by radio
stations, bringing your favorite tunes. Radio waves are also
emitted by stars and gases in space.
• Microwave: Microwave radiation will cook your popcorn in
just a few minutes, but is also used by astronomers to learn
about the structure of nearby galaxies.
• Infrared: Night vision goggles pick up the infrared light
emitted by our skin. In space, infrared light helps us map
the dust between stars.

7. • Ultraviolet: Ultraviolet radiation is emitted by the Sun and
are the reason skin tans and burns. "Hot" objects in space
also emit UV radiation
• X-ray: A dentist uses X-rays to image your teeth, and airport
security uses them to see through your bag. Hot gases in the
Universe also emit X-rays
• Gamma ray: Doctors use gamma-ray in the treatment of
dangerous diseases.

8. The electromagnetic spectrum

10. • EMR in the range of 0.4 µm to 0.7 µm is
known as the visible region
• white light contains a mix of all wavelengths in
the visible region

11. Visible portion of spectrum
• Violet: 0.4 µm to 0.446 µm
• Blue: 0.446 µm to 0.500 µm
• Green: 0.500 µm to 0.578 µm
• Yellow: 0.578 µm to 0.592 µm
• Orange: 0.592 µm to 0.620 µm
• Red: 0.620 µm to 0.7 µm
Among these blue, green and red are the
primary colors

12. • Sir Isaac Newton 1666 passed white light
through a glass prism and concluded that
“white light is a mixture of several other
lights”

13. • The principle behind this is that as radiation
passes from one medium to another it bends
this phenomenon is called refractive index

14. • The process of separating the constituent
colours in white light is known as dispersion

15. • The light which our eyes, our sensors can detect is
part of the visible spectrum
• Some remote sensing instruments also detects
radiations invisible to our eyes
• Range of visible wavelength is from 0.4 µm to 0.7 µm
• Longest visible wavelength is red and shortest is violet

16. • Apart from these three, all other colors can be
formed by combining blue, green and red in
various proportions
• EM spectrum spreads from cosmic rays to
radio waves
• Region of EM spectrum useful in remote
sensing is from ultra violet to microwave

17. USES
• Most parts of the electromagnetic spectrum
are used in science for spectroscopic and
other probing interactions, as ways to study
and characterize matter.
• In addition, radiation from various parts of the
spectrum has found many other uses for
communications and manufacturing